Tree species in tropical rain forests exhibit a rich panoply of spatial patterns that beg ecological explanation. The analysis of tropical census data typically relies on spatial statistics, which ...quantify the average aggregation tendency of a species. In this article we develop a cluster‐based approach that complements traditional spatial statistics in the exploration and analysis of ecological hypotheses for spatial pattern. We apply this technique to six study species within a fully mapped 50‐ha forest census in peninsular Malaysia. For each species we identify the scale(s) of spatial aggregation and the corresponding tree clusters. We study the correlation between cluster locations and abiotic variables such as topography. We find that the distribution of cluster sizes exhibits equilibrium and nonequilibrium behavior depending on species life history. The distribution of tree diameters within clusters also varies according to species life history. At different spatial scales, we find evidence for both niche‐based and dispersal‐limited processes producing spatial pattern. Our methodology for identifying scales of aggregation and clusters is general; we discuss the method’s applicability to spatial problems outside of tropical plant ecology.
The secretome of a parasite in its definitive host can be considered to be its genome
in trans, to the extent that secreted products encoded by the parasite fulfill their function in the host milieu. ...The ‘extended phenotype’ of the filarial parasite,
Brugia malayi, is of particular interest because of the evidence that infection results in potent down-modulation of the host immune response. We collected
B. malayi ‘excretory–secretory’ (BES) proteins from adult parasites and using a combination of shotgun LC–MS/MS and 2D gel electrophoresis, identified 80
B. malayi and two host proteins in BES, of which 31 (38%) were detectable in whole worm extract (BmA). Products which were enriched in BES relative to BmA included phosphatidylethanolamine-binding protein (PEB), leucyl aminopeptidase (LAP, homologue of ES-62 from the related filaria
Acanthocheilonema viteae),
N-acetylglucosaminyltransferase (GlcNAcT) and galectin-1, in addition to the previously described major surface glycoprotein, glutathione peroxidase (gp29, GPX-1) and the cytokine homologue macrophage migration inhibitory factor (MIF-1). One of the most abundant released proteins was triose phosphate isomerase (TPI), yet many other glycolytic enzymes (such as aldolase and GAPDH) were found only in the somatic extract. Among the more prominent novel products identified in BES were a set of 11 small transthyretin-like proteins, and three glutamine-rich-repeat mucin-like proteins. Notably, no evidence was found of any secreted protein corresponding to the genome of the
Wolbachia endosymbiont present in
B. malayi. Western blotting with anti-phosphorylcholine (PC) monoclonal antibody identified that GlcNAcT, and not the ES-62 homologue, is the major PC-bearing protein in BES, while probing with human filariasis sera showed preferential reactivity to galectin-1 and to processed forms of myotactin. Overall, this analysis demonstrates selective release of a suite of newly identified proteins not previously suspected to be involved at the host–parasite interface, and provides important new perspectives on the biology of the filarial parasite.
Borneo, the World's fourth largest island, represents a continental mass sandwiched between volcanic arcs. Patterns of tree species richness, here proposed as proxy for overall biodiversity, and ...endemism within the island are described and interpreted with special reference to Dipterocarpaceae. Most of Borneo's surface is sedimentary shales, mostly inland, and sandstones, mostly coastal, deposited in past epicontinental seas. The shales mainly support the regional West Malesian (Sundaland) tree flora, while the Neogene coastal hills, especially in the north-west, support the richest communities which are also richest in endemics. The forests of these hills, which include the richest tree communities in the Old World and are therefore of global significance, are accessible and critically endangered. Priorities for their future management are outlined.
Exploring the Fasciola hepatica tegument proteome Wilson, R. Alan; Wright, Janelle M.; de Castro-Borges, William ...
International journal for parasitology,
11/2011, Letnik:
41, Številka:
13
Journal Article
Recenzirano
Odprti dostop
Display omitted
► Plasma membranes were detached from the
Fasciola hepatica tegument by freeze/thaw/vortexing. ► Extraction of enriched material with chaotropic agents increased the ...membrane/secretory components to 30%. ► Several novel proteins were identified that are potential vaccine candidates. ► Tegument secretions are overwhelmed by the vomited gut contents.
The surface tegument of the liver fluke
Fasciola hepatica is a syncytial cytoplasmic layer bounded externally by a plasma membrane and covered by a glycocalyx, which constitutes the interface between the parasite and its ruminant host. The tegument’s interaction with the immune system during the fluke’s protracted migration from the gut lumen through the peritoneal cavity and liver parenchyma to the lumen of the bile duct, plays a key role in the fluke’s establishment or elimination. However, little is known about proteins of the tegument surface or its secretions. We applied techniques developed for the blood fluke,
Schistosoma mansoni, to enrich a tegument surface membrane preparation and analyse its composition by tandem mass spectrometry using new transcript databases for
F. hepatica. We increased the membrane and secretory pathway components of the final preparation to ∼30%, whilst eliminating contaminating proteases. We identified a series of proteins or transcripts shared with the schistosome tegument including annexins, a tetraspanin, carbonic anhydrase and an orthologue of a host protein (CD59) that inhibits complement fixation. Unique to
F. hepatica, we also found proteins with lectin, cubulin and von Willebrand factor domains plus 10 proteins with leader sequences or transmembrane helices. Many of these surface proteins are potential vaccine candidates. We were hampered in collecting tegument secretions by the propensity of liver flukes, unlike blood flukes, to vomit their gut contents. We analysed both the ‘vomitus’ and a second supernatant released from haematin-depleted flukes. We identified many proteases, some novel, as well as a second protein with a von Willebrand factor domain. This study demonstrates that components of the tegumental surface of
F. hepatica can be defined using proteomic approaches, but also indicates the need to prevent vomiting if tegument secretions are to be characterised.
In the southern mountain ranges of Yunnan province, China, deep valleys of several large rivers create rain shadows with hot dry summers, and are locally designated tropical; towards the north, ...notably in the Lancang (Upper Mekong) valley, these regions may experience frost during winter. The woody forest canopy of these valleys is predominantly deciduous, with evergreen elements in the north, where the canopy is open and the forest savanna-like. However, we here present tall forest with a closed deciduous canopy and semi-evergreen subcanopy observed in hot dry valleys of these rivers and their tributaries in the tropical south. The structure and physiognomy of these forests resemble the tall (moist) deciduous forest formation widespread in South Asia and Indo-Burma. Furthermore, these forests are largely composed of tropical elements at both the generic (80%) and the species level (>70%), indicating that these forests are indeed tropical. We originally hypothesized that these isolated forests represent refugia of a pre-Holocene extension of tall (moist) deciduous forest formation of South Asia and Indo-Burma. The sample plot we established to test this hypothesis confirmed that these forests share the structure and physiognomy of the tall (moist) deciduous forest formation; however, the plots also showed that these forests lack the characteristic and dominant species of the formation's Indo-Burmese range. The tree flora, in particular, indicates that both deciduous and evergreen elements are instead mostly derived from the adjacent tropical semi-evergreen forests of tropical southern China; yet they also include an important endemic element, which implies that these forests have survived as refuges possibly since the Pliocene. The exceptional representation of evergreen elements in these forests indicates that they have rarely been subject to hot fires or domestic cattle browsing, adding to the unique nature of the forests and further justifying their strict conservation.
•Floristic composition, physiognomy and biogeography of the tropical deciduous forest in SW China are studied.•That the forest represents refugia of a pre-Holocene extension of this widespread formation is hypothesized.•The biogeography of the forest shows connection with the geological and climatic history of these regions.
Different mechanisms have been proposed to explain how vertical and horizontal heterogeneity in light conditions enhances tree species coexistence in forest ecosystems. The foliage partitioning ...theory proposes that differentiation in vertical foliage distribution, caused by an interspecific variation in mortality-to-growth ratio, promotes stable coexistence. In contrast, successional niche theory posits that horizontal light heterogeneity, caused by gap dynamics, enhances species coexistence through an interspecific trade-off between growth rate and survival. To distinguish between these theories of species coexistence, we analyzed tree inventory data for 370 species from the 50-ha plot in Pasoh Forest Reserve, Malaysia. We used community-wide Bayesian models to quantify size-dependent growth rate and mortality of every species. We compared the observed size distributions and the projected distributions from size-dependent demographic rates. We found that the observed size distributions were not simply correlated with the rate of population increase but were related to demographic properties such as size growth rate and mortality. Species with low relative abundance of juveniles in size distribution showed high growth rate and low mortality at small tree sizes and low per-capita recruitment rate. Overall, our findings were in accordance with those predicted by foliage partitioning theory.
Luminescent Ln−Pt2 metallohairpin complexes have been developed, and their intercalative recognition with DNA has been demonstrated with linear dichroism spectroscopy. The heterotrimetallic complexes ...were formed in a one-step reaction, by assembly of an aminopolycarboxylate ligand, a platinum terpyridine unit, and the lanthanide salt. The metallohairpin complexes bear a neutral lanthanide moiety and two positively charged platinum-containing intercalating units. The Nd(III) analogues are luminescent in the near infrared, and this near-IR luminescence is retained upon binding to DNA. The DNA recognition was demonstrated by linear dichroism spectroscopy. The linear dichroism spectra suggested that the complexes bind perpendicular to the DNA helical axis, confirming intercalative recognition accompanied by dramatic stiffening of DNA, which suggests bis-intercalation of the complex.
A conserved structural feature of human IgG molecules is the presence of an oligosaccharide moiety within the Fc region at Asn297. In addition, 15–20% of normal polyclonal IgG molecules bear N-linked ...oligosaccharides in the variable (V) regions of the light (L) and/or heavy (H) chains. Electrospray ionization mass spectrometry (ESI-MS) has been applied to the glycan analysis of two IgG1 myeloma proteins (Wid and Cri) after mild reduction and acidification. Heterogeneous ion peaks were observed for both the H and L chains of Wid in contrast to Cri whose L chain peak was homogeneous. Site-specific deglycosylation of the H and L chains of IgG Wid was achieved under native conditions with peptide-
N-glycosidase F and endoglycosidase F2, respectively. The Fc glycoforms differed between the two proteins in that Cri-Fc bears diantennary complex-type glycans that are fully core-fucosylated and partially sialylated while Wid-Fc glycans are non-fucosylated, partially galactosylated and non-sialylated. In contrast to the Fc glycans, the L chain glycans of Wid were shown to be fucosylated, fully galactosylated and sialylated, indicating that the glycosylation machinery of the Wid-producing myeloma cells is intact. Thus, combination of the two endoglycosidases can provide a simple means of glycan analysis of both Fab and Fc by ESI-MS, which may contribute to the development of therapeutic IgG with customized glycan profiles.
Some 85% of Africa's water resources are comprised of large river basins that are shared between several countries. High rates of population growth accompanied by continued increases in the demand ...for water have resulted in several countries passing the point where the scarcity of water supplies effectively limits further development. Present population trends and patterns of water use suggest that more African countries will exceed the limits of their economically usable, land-based water resources before 2025. Normally, water allocation and distribution priorities within a country are aligned with national development objectives. While this may achieve national “water security” objectives, greater emphasis needs to be placed on regional efforts to ensure that the available water resources are used to derive sustainable long-term benefits for the peoples of Africa as a whole. Ideally, each country's water-resource management strategy needs to be aligned with that of its neighbors if peace and prosperity are to be maintained and conflict is to be avoided in the region.
Schistosoma mansoni is a well-adapted blood-dwelling parasitic helminth, persisting for decades in its human host despite being continually exposed to potential immune attack. Here, we describe in ...detail micro-exon genes (MEG) in S. mansoni, some present in multiple copies, which represent a novel molecular system for creating protein variation through the alternate splicing of short (< or =36 bp) symmetric exons organized in tandem. Analysis of three closely related copies of one MEG family allowed us to trace several evolutionary events and propose a mechanism for micro-exon generation and diversification. Microarray experiments show that the majority of MEGs are up-regulated in life cycle stages associated with establishment in the mammalian host after skin penetration. Sequencing of RT-PCR products allowed the description of several alternate splice forms of micro-exon genes, highlighting the potential use of these transcripts to generate a complex pool of protein variants. We obtained direct evidence for the existence of such pools by proteomic analysis of secretions from migrating schistosomula and mature eggs. Whole-mount in situ hybridization and immunolocalization showed that MEG transcripts and proteins were restricted to glands or epithelia exposed to the external environment. The ability of schistosomes to produce a complex pool of variant proteins aligns them with the other major groups of blood parasites, but using a completely different mechanism. We believe that our data open a new chapter in the study of immune evasion by schistosomes, and their ability to generate variant proteins could represent a significant obstacle to vaccine development.
PDF
